Piston



Dec1 `4, 1945.

Original Filed Dec. 11,` 1942 ne 1 M /K @hw m5. M .7@

A TTORNEYJ' Patented nee. 4, 194s UNITED STATES N PATENT OFFICE g 5 ww:

nvmxamrsrmrlmame. riginll application December 11, 1942, Serial Divided and this application October 9, 1943, Serlll No. 505,599

10 Claims.

This invention relates to improvements in pistons.

This application is a division of my copending application Serial No. 468,623, tiled December 11, 1942, for Piston and method of making the same.

The main objects of this invention are: First, to provide an internal combustion engine piston having a large transfer of heat from the the combustion chamberis relatively great compared to that of the metal beneath, and in which the bonding contact between the adjacent surfaces of said metals is of a nature. first to insurel a maximum transfer of heat from one metal to the other, and second to insure against separation of said metals when subject to the stress of high reciprocating speeds and long continued Third, to provide a piston having a laminated 3 piston then appearing as in Fig. 3. In the-em-` structure of the character above described which can be made at a relatively low cost 'in large quantities, and of uniform quality as to homogeneity of bond, uniform thickness, and purity of metal top to insure a strong bond between the metals and a maximum transfer of heat.

Further objects pertaining to details and economies will deiinitely appear from the description to follow. The invention is defined in the claims.

In the accompanying drawing I illustrate my improved pistonvand a part of the apparatus and certain steps in the method of. producingthe' piston. 1

Fig. 1 is a side view of one embodiment of the piston with parts broken away to show the head of the piston in central ,vertical section.

Fig. 2 is a detail view in central vertical section illustrating anotherembodiment of the piaton.

Fig. 3 is a side view of a piston as cast, with .parts broken away and illustrating the piston before a depression hasbeen machined in the top thereof furthe reception o! a flux and copper granules.

Pig.4isacentralverticalsectionalviewofthe 55 Thepiston I withuxtandcopper Ainthe head of the piston after one form of depression has been machined into the top thereof.

Fig. 5 is a central vertical sectional view of ,the head of the piston after a modied form 5 of depression has been machined into the top thereof.

Fig. 6 is a fragmentary view, showing the machined piston of Fig. 4 relative to a heating element of an electric furnace.

Fig. '7 isa view similar to Fig. 4 after the depression of the piston is lled with a flux and copper granules.

Fig. 8 shows conventionally an electric furnace designed for operation at approximately the temperature indicated on the drawing.

Figs. 9, 10 and ll each show conventionally `electric furnaces or cooling chambers designed for operating at approximately the temperature indicated on the drawing.

zo Fig. 12 is a detail vertical sectional view of the embodiment of the piston shown in Fig. '1, showing the copper united to the piston body after the heating and cooling steps.

I will now describe the piston and the steps of the method of producing the same in reference y to the accompanying drawing, in which the numeral l designates a piston casting having a head 2 and a skirt 3. The piston may be cast in the usual manner of foundry practice, the

bodiment of the invention shown in Figs. 1, 4, '1 and 12, I turnout the depression 5 in the head of the piston by means of a lathe centered at I, leaving a pilot or central raised portion 6, .35 about the center l and also leaving the peripheral 0 preferably by sand blasting, to remove the carhon-like smudge. Unless this lm smudge iscomand iron is not likelyto be uniform nor closely knit to stand the stress of use in lan engine, which involves various factors.

After thoroughly cleaning, the machined surface of depression 5 is thinly coated with a suitable ux, indicated at 8 in Fig. '1, a flux mixture of borax and manganese dioxide being suitable. Granules of pure copper IA or copper bars are then placed in the depression 5, in such quantity as is calculated to iill said depression to the proper depth with molten copper, after the heating operation later described.

y ventionally shown in Fig. 8 and operative at a temperature of 2050 degrees Fahr. or above the melting point oi' copper. At this temperature the copper is sufficiently fluid and the iron expanded to such a degree as to permit the fluid copper to enter the pores of the iron to a substantial depth;

Within a short period of time, ve minutes are found to be a desirable period, after the copper is in a thoroughly iiuid state such as would permit the same to flow over the surface of thedepression, thepiston I with the molten copper in the depression 5 is removed from the electric furnace I0 and is cooled in successive stages in the cooling chambers. The rst cooling chamber II, conventionally shown `in Fig. 9, is maintained at a temperature degrees Fahr. The work is then placed in chamber I2, shown in Fig. 10, operating at a temperature of approximately 1000 degreesv Fahr., and finally in chamber I3, shown in Fig. 12,l operating at a temperature of approximately 130 degrees Fahr. An electric heating element I4 and its relation to a piston is shown conventionally in Fig. 6.

The above described cooling stages are highly important for the best bonding contact between the copper and the iron, since they have the important function f maintaining integral connection between the body of of -the iron beneath, otherwise the rapid and unequal degreesv of contraction of the iron and the copper would more or less break or weaken the connection. Said cooling stages also prevent the iron part of the piston from warping from shape and from becoming too hard 'andbrittle. As a further step highly important in improving the bonding contact between the copper and the iron and also the 'purity of the metals, and' thereby increasing strength and h`eat transferrence, the heating operation in the electric furnace I 0 and the first two cooling stages in cham-` bers II and I2 are in an atmosphere free of oxygen or other gas that dlze or affect said metals. Such an atmosphere may preferably b e a deoxidizing one, as hydrogen. This gas not only prevents. formation otl oxides but also reduces to a pure metallic state any metallic oxides that may exist in said metals. Finally after completion of the above described operations, the piston is turned to proper size, the retaining ledge 1. being,cut away in this operation. Also the of copper 9 is chamfered at I5, as shown in Fig. 1. In the embodiments of the invention shown in Figs. 1, 4, 7 and l2, the same lathe center 4 and pilot 6 used in machining the depression 5 in the head 2 of the piston may also be used in these final machining operations, including the cutting of the ring grooves I6.

In the embodiment of the invention shown in Figs. 2 and 5, the central raised portion 6 of the mbodiment of Figs. 1, 4. 7 and 12 is omitted, the depression I1 being machined inthe head of the piston to leave only the peripheral retaining ledge I8. In the completed piston, as shown in Fig. 2, the layer of copper I9 extends over the 'central portion' of the head and completely covers the combustion surface fbodiments of Figs. 2 and- 5 and the mannerot of the piston. The emproducing the same is otherwisev similafto the embodiment of Figs. 1, 4, 7 and 12.

peripheral edge of the layer s greatly strengthens of approximately 1600 so that it not only is vides an effective heat the copper 9 above the iron and the copper in the pores of the body might detrimentauy 6x1- .tially the entire of the copper and In the pistons produced by the above dcscribed method, the copper has permeated thev pores of the iron to such an extent and depth as to be visible in the body of the iron, like splashes of copper paint. In Figs. 1, 2 and 12 the copper is shown at 20 4as extending from the body of the copper into the body, of the 'iron beneath. I'he filling up of the microscopic voids in the iron extending for a substantial distance from the body of the copper into the iron beneaththe bond between the metals and also facilitates heat transmission from the copper to the iron. tion reference has been made to the body of the piston as being composed of iron,'bu t other suitable material or ferrous alloy may be used instead. and also other suitable metal substituted for the copper.V

The piston of my invention is highly eillcient for the purpose intended, that of diffusing heat preventing lits overheating, is bonded to the iron body securely retained but protransfer bond.

Having thusfdescribed my invention, what I claim as new and desire to secure by Letters Patent is:

1. A piston'i'or internal combustion engines comprising a head portion of cast iron extending across the top of the piston and a layer of copper on said body portion covering substanarea thereof, said layer of copper having integral filament-like portions extending fora substantial distance into the pores of the cast iron head portion, providing a direct heat transfer from said copper layer through the integral filaments thereof into the Ipores of the and thev copper layer iron of the head portion. and providing a fixed- 'said cast iron head portion.

2. A piston for internal combustion engines comprising a head portion of cast iron extending across the top of the piston and a layer of copper on said head portion covering substantially the entire area thereof, said layer of copper having integral portions pores of the cast iron head portion and providing direct heat transfer contact between the layer the cast iron head portion and providing 4a xed bonding connection for said layer of copper to said cast iron head portion.

3. A piston for internal combustion rengines comprising a head portion of iron extending across the top of'. the piston and a layer of copper on said head portion covering substantially the entire area therepf, said'layer of ral portions thereof extending into the pores of the iron vof the head portion providing a direct heat transfer contact therebetween and providing a fixed bonding connection between said layer of copper and said iron head portion.

' 4. A piston for internal combustion engines comprising ahead portion of ferrous metal extending across the top of the piston and a layer of copper on said head portion covering substantially the entire area thereof and extending .to the periphery thereof.- said copper layer' having integral portions thereof extending for a substantial distance into the pores of the ferrous metal of the head portion providing a heat transfer bond A contact and a xed securing connection between the layer of copper and-said head portion of ferrous metal.

5. A piston. for internal combustion engines comprising a head portion of ferrous metal ex- In the foregoing descripthereof extending into the` copper having integ- I a direct heat tending across the top of the piston and a layer of copper on said head portion covering substantially the entire area thereof, said copper having integral pigment-like portions thereof extending for a substantial distance into the pores of the ferrous metal of the head portion providing transfer from said layer of copper, through the integralfilaments thereof into the pores of the ferrous metal of the head portion and providing a fixed bonding contact between said layer of copper and the ferrous metal of the head portion.

` A6. A piston for internal combustion engines comprising a head portion of iron extending across the top of the piston, said head portion having an integral central raised portion of relatively small diameter, a layer of copper surrounding said i ralied portion and covering substantially the en.

area of said head portion, said layer of copper having integral filament-like portions therepores of the iron of the head portion, providing a direct heat transfer from said copper layer, through the integral nlaments thereof into the pores of the iron of the head portion, and providing a xed bonding connection 4between said layer of copper and said iron head portion.

'1. A piston for internal combustion enginesl v al. through the integral filaments thereof into the pores of the ferrous metal of the head portion, and providing for a fixed bonding connection between said layer andsaidheadportion.

layer ,of extending for a substantial distance into the and providing a said layer ofnon-ferrous metal and the irregu- 8. A piston for internal combustion engines comprising a continuous head portion of ferrous metal extending across thickness and rigidity asto resist the explosive forces in use, and a layer of copper of substantial thickness covering substantially. the entire area of the top of the piston, the copper of said layer being cast welded directly to the ferrous metal covered thereby and having cast welded bonding engagement with the ferrous metal providing a direct heat transfer therebetween and providing a fixed bonding connection between the layer of copper and the ferrous metal contacted thereby.

9. A piston for internal combustion engines comprising a continuous head portion of ferrous metal extending across the piston and of such thickness and rigidity as to resist the explosive forces inuse, and a layer of copper of substantial thickness in superimposed relation to said head and covering substantially the entire area thereof, the copper of said layer being cast welded to the ferrous metal of said head portion and having integral filaments thereof in interlocking engagement with the interspaces of the ferrous metal. 5

10. A piston for internal combustionengines comprising a continuous head portion of ferrous metal extending across the top of the piston and rigidity as to resist the explosive forces in use, d a layer of non-ferrous metal having a higher heat conductivity than the ferrous metal and a lower fusion point cast welded to said. ferrous metal head portion and covering substantially the entire area thereof,` said layer of non-ferrous metal being of substantial thickness and having integral portions thereof in 'inlarities of said ferrous metal.

IRVING E. ABRE.

the piston and of such 

